Sprint sues cable companies over digital phone patents

Number-three mobile operator Sprint has filed separate lawsuits against Time Warner, Comcast, Cox Communications, and Cable One, alleging the companies violate a dozen Sprint patents related to digital phone technology. The patents in the suits date back to the 1990s, and some of them are the same patents that Sprint used back in 2007 to extract an $80 million settlement from Vonage over its VoIP operations.

In all the complaints, Sprint says the cable operators “have realized the great value in this technology and have misappropriated it without Sprint’s permission.”

All four of the cable operators named in the suit offer voice services as part of their service bundling deals, which also include broadband Internet access as well as cable television services. Cable companies’ voice offerings are based on VoIP technologies, rather than traditional copper phone lines installed and maintained by phone companies.

The weak link in cable companies’ “triple play” of TV, Internet, and voice was always mobile services, and in the past Sprint was happy to partner with cable operators to add mobile services to their lineup and try to lure consumers with “quadruple plays.” Sprint even convinced companies like Comcast to invest in Clearwire’s build-out of a 4G WiMax broadband network and resell Clearwire services, although Sprint remained Clearwire’s dominant investor. However, in the last few years cable operators have generally pulled away from Sprint, and several cable companies just